The output is correct in both modern GL3 and hardware accelerated software 2D rendering.
It is not correct in GL2 and software 2D rendering.
The reason is that these textures are 24 bit grayscale textures.
Here's the problem: For both these modes the texture needs to be translated into an alpha texture - and that simply fails because the texture manager does not know how to do it.
Alpha textures that work correctly in all modes need proper setup:
1. They need to be 8 bit grayscale (not 24 and not 32 bit!)
2. They need an alPh chunk so that the texture manager knows that they are to be used as an alpha texture. (This is only needed for the software renderer.)
Since the problem only occurs in the two legacy render paths I am not going to throw more code at it as it'd be a very non-trivial fix. As time goes by all this stuff will sooner or later become unnecessary anyway while this hardware slowly disappears completely.
I think the only good this shows is that the market share of GL2 hardware isn't that high anymore, or more people would reported this long ago.
The output is correct in both modern GL3 and hardware accelerated software 2D rendering.
It is not correct in GL2 and software 2D rendering.
The reason is that these textures are 24 bit grayscale textures.
Here's the problem: For both these modes the texture needs to be translated into an alpha texture - and that simply fails because the texture manager does not know how to do it.
Alpha textures that work correctly in all modes need proper setup:
1. They need to be 8 bit grayscale (not 24 and not 32 bit!)
2. They need an alPh chunk so that the texture manager knows that they are to be used as an alpha texture. (This is only needed for the software renderer.)
Since the problem only occurs in the two legacy render paths I am not going to throw more code at it as it'd be a very non-trivial fix. As time goes by all this stuff will sooner or later become unnecessary anyway while this hardware slowly disappears completely.
I think the only good this shows is that the market share of GL2 hardware isn't that high anymore, or more people would reported this long ago. :)